Different types and/or styles of cartridge ejection mechanisms or “ejectors” are utilized in various types of firearms. Some are integral to the firearm bolt (e.g., a “plunger-style” ejector) while others are integral to the receiver assembly. While each available style provides differing benefits and drawbacks, many prefer the simplicity and bolt-integral nature and operating characteristics of the plunger-style ejector.
Most firearms utilize a bolt with a planar face that is designed to mate with a corresponding planar face of a breech, barrel extension, and/or firing chamber (e.g., to seal a cartridge in the chamber for firing). It is understood however, that a tapered or cone-shaped mating configuration is advantageous. Tapering the face of the bolt and providing a cone-shaped breech, for example, provides a less obstructive path for feeding cartridges into the firing chamber, provides for an increased surface contact mating area between the bolt and the breech, and/or permits decreased levels of cartridge case protrusion. These advantages allow for (i) more reliable cartridge feeding (e.g., less jamming and/or cartridge damage upon feeding), (ii) increased contact area that provides an enhanced seal that is less likely to result in blowback or structural failure, and (iii) increased cartridge case contact with the chamber that minimizes the likelihood of catastrophic cartridge failure, respectively.
Despite these recognized advantages, most firearms do not utilize a cone-shaped breech. This is primarily due to the fact that tapered bolt configurations capable of use in cone-shaped breech systems are not capable of functioning properly in repeating firearms, particularly in conjunction with a plunger-style ejector. In other words, magazine and clip-feed firearms that are designed to store and repeatedly load, fire, and eject cartridges in a repeating fashion are unable to benefit from the advantages of a cone-breech design, especially when combined with a plunger-style ejector, due to interference with cartridge loading.
Semi-automatic firearms suffer from other deficiencies inherent in their design and functionality. Semi-automatic firearm bolts with multiple locking lugs, such as those utilized in AR-15/M-16 models for example, sacrifice locking lug strength and/or integrity due to extractor design and configuration. The standard AR-15/M-16 bolt comprises seven (7) locking lugs, for example, such that forces acting upon the lugs due to firearm operation are distributed over each of the seven (7) lugs. While it is desirable to distribute the forces acting upon such locking lugs amongst more lugs and/or across more material (for increased strength and reliability), the necessity of the typical extractor requires that the material where an eighth (8th) lug could be formed be removed. In an effort to mediate this deficiency, the standard extractor comprises a raised portion on the bolt-face end to simulate an eight (8th) locking lug.